1. Field of Invention
This invention relates to pogo stick type exercising devices, and specifically to those that use a pneumatic cylinder as an air spring.
2. Description of Prior Art
Pneumatic air cylinder technology is a well known and highly developed art due to extensive use in many industrial applications. For this reason, modern air cylinders are both reliable and durable, with life expectancies commonly measured in the millions of cycles. It therefore seems reasonable to apply this technology to exercise equipment, and particularly to rebounding devices.
Pogo sticks are a well known recreational toy. During this century, patents in this field have described numerous methods of obtaining a higher or more controllable leap. Most of these have involved complicated mechanisms which raise questions as to their reliability as well as high costs to produce.
One example of a pneumatic pogo stick is found in U.S. Pat. No. 4,632,371 issued to Wirges, et al., Dec. 30, 1986, and names over 200 parts. Of a similar nature is U.S. Pat. No. 3,351,342 granted to Guin Nov. 7, 1967. Each of these patents provides a pogo stick that uses a pneumatic "air spring" with a biasing force that is variable. Other than complexity and obvious expense to build, both these patents share another shortcoming: their designs allow for varying only the biasing force, and have no provision for variation of the elevation, or extendability of the air spring.
One U.S. patent attempts to address the problem of variable height control, but does so in a very limited way. U.S. Pat. No. 3,181,862 (White, May 4, 1965) describes a pogo stick of great mechanical complexity that uses a rack and sprocket to raise or lower the mechanism, one tooth per jump, for a total extension of about 50 centimeters (20 in.). Presumably, this limited extendability is due to limitations of design as well as necessary skills required to operate without damaging the device or the operator. The skill factor here is important, as it also brings up the question of safety.
The safety issue has become increasingly important in recent times due to the legal climate of more lawsuits and greater awards. Any marketing venture that fails to recognize this factor is therefore in danger of commercial failure. Prior patents in the pogo stick field have, for the most part failed to address this issue. There is an element of danger inherent in devices that enable people to be propelled into the air without restraint. Heretofore, a certain degree of skill was assumed in order for the operator to safely complete a series of jumps. Good judgment was also required in selecting terrain, surface conditions, etc., as well as an awareness of people, vehicles, or other hazards in the area. Also, the device itself could be an additional hazard, the more so if heavy, or prone to uncontrolled flight when the operator fell off.
I have found no prior art that uses a stationary, or secured version of a pogo stick to overcome these problems. Additionally, sharp or unpadded surface could be especially dangerous in pogo sticks that are short enough to allow the head of the rider to extend above the top of the device. This would expose the head, face, and neck to serious injury should the feet slip from the footrests, or the knees flex during recoil. This shortcoming appears to be present in two, of not all three of the above cited references.